Modification of discharge sequences to control the random dispersion of flake particles during wafer etching

Abstract

During the etching of the dielectric layer of semiconductors through plasma etching, numerous flake particles are generated in the etching equipment. These particles cause layout defects on the wafer and engender reduced yield on production lines. Accordingly, this study investigated how such flake particles could form in a chamber involving varying levels of deterioration on the electrostatic chuck surface and varying levels of by-product deposition. Moreover, we tested the effect of various electrostatic chuck discharge sequences and voltages on the deposition of these flake particles. Our experimental results revealed that selecting an appropriate radiofrequency power and a voltage discharge sequence protocol for the electrostatic chuck and using a low-frequency radiofrequency power supply could minimize the number of flake particles adhering to a wafer surface. In the proposed method, wafer contamination is controlled by suppressing unstable electric stress that arises when the etching chamber is coated with deposited by-products and the electrostatic chuck has a deteriorated surface.